drm/i915/gvt: Add missing symbol export.

When CONFIG_DRM_I915_DEBUG_RUNTIME and CONFIG_DRM_I915_DEBUG_PM
are enabled, two more extra symols in i915 are required to be
exported.

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20220425220331.24865-1-zhi.a.wang@intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>